1. Field of the Invention
The present invention generally relates to a medicinal liquid injection catheter that can inject an appropriate medicinal liquid to a lesion.
2. Discussion of Related Art
A catheter has conventionally been used as a medical device that is inserted, for the purpose of medical treatment or examination, in a human being's tubular organs such as blood vessel, digestive tract, urinary duct, trachea, or bile duct, or other body cavities or tissues. In addition, recently, such a catheter that employs a balloon at an end portion thereof where the balloon is inflatable and deflatable, is usefully used for so-called PTCA (percutaneous transluminal coronary angioplasty) known as a safe method for treating, for example, cardiac infarction or stenocardia. As well known, PTCA is carried out in such a manner that the catheter with the balloon is inserted in a stenotic portion of heart's coronary artery, and the balloon is inflated to push and widen the stenotic portion and thereby improve the flow of blood to the cardiac muscle.
More recently, there are various proposals to use a catheter as a medical device for injecting an appropriate medicinal liquid to a lesion of tissues, e.g., a blood vessel or a tissue near a blood vessel. For example, Japanese Patent Document (Laid-Open Publication) No. 2001-299927 proposes a medicinal liquid injection catheter that employs the above-mentioned balloon.
More specifically described, the medicinal liquid injection catheter disclosed by the above-indicated document includes a tubular main body having a side hole in a side surface thereof (the main body is called a shaft in the document) and a needle-like tubular member (the tubular member is called an introduction needle in the document) that is provided by a flexible, elongate thin tube whose end portion provides a needle portion. The tubular member is inserted and placed in the main body and is movable relative to the main body in a lengthwise direction thereof so that the needle portion projects outward from the side hole of the main body. The medicinal liquid injection catheter also includes a balloon externally attached to the main body to be inflatable and deflatable (the balloon is called an expansible portion in the document).
The medicinal liquid injection catheter having the above-described arrangement assures that the main body is inserted in a blood vessel, then the balloon is expanded to contact and press the blood vessel's wall to prevent the movement of the main body in the blood vessel. In this state, the needle portion of the needle-like tubular member is pushed outward from the side hole of the main body so as to needle a treated lesion. Therefore, the medicinal liquid injection catheter can be used to inject, through the needle-like tubular member, the appropriate medicinal liquid to the lesion.
As explained above, recently, the medicinal liquid injection catheter has been used. However, there has been a demand for a medicinal liquid injection catheter that assures that a main body thereof is fixedly held at a desired position in a tubular organ such as a blood vessel and a needle portion thereof accurately needles a lesion to be treated.